FAMILIAL LUNG-DISEASE ASSOCIATED WITH PROLIFERATION AND DESQUAMATION OF TYPE-II PNEUMONOCYTES

A family is described in which certain infants presented with a diffuse parenchymal pulmonary disorder characterized by proliferation and desquamation of alveolar epithelial cells that progressed to severe pulmonary fibrosis and cystic dysplasia, resulting in "honeycomb" lung typical of chronic pulmonary interstitial disease (idiopathic pulmonary fibrosis) at death. Electron microscopic examination of a lung biopsy specimen from one infant revealed that the proliferating/desquamating cells were ultrastructurally normal-appearing type II pneumonocytes with osmiophilic lamellar bodies. This patient did not respond to prednisone therapy, but she showed great improvement with chloroquine therapy, which was confirmed by a repeated lung biopsy. Possible mechanisms that might account for the effect of chloroquine, such as inhibition of DNA synthesis, as well as the cellular pathobiology of type II pneumonocyte proliferation in this disease, are discussed.